The present invention relates to a projector system and, more particularly, to a projector system using two liquid crystal projectors, which combines images projected by the two liquid crystal projectors.
In a conventional method of improving brightness of a projection screen, a pair of liquid crystal projectors are juxtaposed such that images from these projectors are combined on the screen by adjusting angles and focuses of projection lenses of the projectors. In this method, however, the adjustment must be performed every time when a projecting distance is changed since optical axes of these liquid crystal projectors are not coincident with each other. Further, peripheral portions of the images on the screen are not consistent with each other due to trapesoidal distortion of the images.
In order to solve these problems, Japanese Patent Application Laid-open No. H5-66502 (1993) proposes a liquid crystal projector system. FIG. 4 is a plan view of the proposed liquid crystal projector system. In FIG. 4, the liquid crystal projector system includes a liquid crystal projector 40 having an S polarizing projection lens 41 which emits an S polarized light, and a liquid crystal projector 50 having a P polarizing projection lens 51 which emits a P polarized light. Then, the S and P polarized lights are combined by a polarized light beam splitter 60' and projected onto a projection screen 70'.
In the liquid crystal projector system shown in FIG. 4, the S polarization liquid crystal projector 40 and the P polarization liquid crystal projector 50 are arranged such that a virtual flat plane containing optical axes 42 and 52 of the projection lenses 41 and 51 of the respective S and P polarization liquid crystal projectors 40 and 50 is parallel to a long (major) side direction of the projection screen 70'. Incidentally, the major side direction of the projection screen is a lateral or horizontal direction shown in FIG. 4 by a double arrow.
In this case, an incident angle of light from the lens, for example, lens 51, to a polarized light combining plane 61' of the polarization beam splitter 60' varies substantially in the major side direction of the projection screen. Further, it has been known that spectral characteristics of the polarization beam splitter 60' has an incident angle dependency and is changed with deviation of the light incident angle from 45 degree, as shown in FIG. 3. Therefore, when the light incident angle is deviated from 45 degree, there may be produced an unevenness of image color in the major side direction of the projection screen.